Air compressor



Aug. 18, 1931. A. J. RIX 1,819,691

AIR COMPRESSOR Filed May 7, 1930 2 Shets-Sheet l INVENTOR.

BY 2 1 A TTORNEYS.

Aug. 18, 1931. A. JVRIX 1,819,691

1 AIR COMPRESSOR Filed May 7, 1930 2 Sheets-Sheet 2 F a u. 3-- -L|L-u.L'

1/ INVENTOR.

i l I BY 1 mml WW ATTORNEYS. 9

Patented Aug. 18, 1931 UNITED STATES AUsTINa IX, or sAN FRANOiSCO,CALIFORNIA AIR comrnnssoa App1ication filed May 7 1930. Serial N;450,390.

This invention relates to-air compressors and especially to a directconnectedmotor driven air compressor with mechanically actuated inletand discharge valves.

E l Vhen the automatic duo plate air valves were first introduced on thevertically socalled high speed air compressors the speeds ranged from400 to 500 R. P. M. and the lift of the valves were of sufficient heightto pro- .10 vide the same area as the port openings in the valve seatsso as to permit flow of air in and out of the cylinders without unduevelocity or resistance. As the air compressor industry progressed themain trend has been towards '1 higher speeds and lighter weights. Inorder to obtain these speeds lighter and stronger reciprocating partswere necessary, Automotive practice was followed in designing thereciprocating parts with the result that high- 2 er speeds were obtainedand construction generally improved but the valve mechanism wasneglected. This resulted in valve breakage developed by rapidmovement ofthe concentric valve plates and in order to overcome '3 this trouble theliftof the valves were materially reduced and in some instances "cut inone-half, thereby reducing the lift area and causing air passagerestriction. This of course resulted in loss in eificiency caused by 0high cylinder pressures and temperatures and it also caused excesscarbon deposits from the lubricating oils, increased horsepowerconsumption and the use of larger radiators for cooling purposes. Itmight also be stated that with duo plate types of valves there are large.45 ly800 R. P. M., hence if a gas engine or the like is directconnected to the compressor all the power of the engine is not availableasthe majority of engines are designed to operate at speeds of 1200 to1500 R. P. M. and 0 where electric motors are direct connected to thecompressor it is necessary to employa 900 R. P. M. motor which is costlyand heavy as stock motors operate around 1750 R. P. M. The object of thepresent inventionis to generally improve and simplify the con- 5struction and operation of air compressors and particularly that typewhich is adapted to bezdirect connected to a source of motive power suchas an engine or motor; to provide a compressor capable of eiiicientopera- 5 tion at engine or motor speeds, for instance, 12003. P. M. ormore; to provide acompressor in which the clearance volume between thetop of the piston and the head of the valve mechanism carried therebymay be greatly reduced; to provide a compressor in i which the valvesare mechanically actuated;

to provide a compressor in which valves of large area and lift may beemployed; to provide a compressor which is adapted for direct connectionwith internal combustion engines or the like and in fact adapted to bebuilt as an integral part thereof; to provide a direct connectedcompressor in which the valves are adapted to be actuated by the camshaft of the internal combustion engine; and further, to provideacompressor in whichthe inlet valve is adapted to be held in an openposition by an unloader mechanism. Further objects will hereinafterappear.

H The invention is shown by Way of illustration in the accompanyingdrawings, in Wh1chv Fig. 1 1s a side elevation of a dlrect connectedengine and air compressor, said side elevation being partially brokenaway to show partsv ofthe mechanism insection,

Fig. 2. is a vertical cross section of one of the air compressingcylinders, and v Fig. 3 is an enlarged cross section of the aircompressor head showing the inlet valve and its actuating mechanism.

Referring to the drawings in detail and particularly Fig. 1, A indicatesthe cylinders of an internal combustion engine of the fourcycle type, Bthe crank shaft, C the cam shaft, which in this instance is driven fromthe crank shaft by :gears 2 and 3 in the usual manner; the speed ratiobetween the crank shaft and camshaft being two to one. The

crank case generally indicated at D which supports the cylinders A andthe crank shaft B is, in this instance, extended to support a pair ofair compressor cylinders generally indicated at E and F. Each cylinderis provided with a piston such as shown at 5 and as the crank shaft B isextended to provide two additional cranks such as shown at 6 and 7 thepistons 5 will be connected through rods 8 with the respective cranksand as such will move in unison with the pistons in the cylindersindicated at A. The cylinders E and F are identical in construction.They are both provided with inlet and discharge valves such as indicatedat 9 and 10, respectively, these valves being mechanically operated froman extension of the cam shaft C hereinafter to be described.

The valves employed are poppet valves such as used in automotivepractice, the inlet valve opening inwardly in the usual manner and beingoperated by a rocker arm 9a of the usual type as shown in Fig. 3. Thedischarge valve on the other hand sits on top of the cylinder and opensupwardly and a slightly modified form of rocker arm is accordinglyrequired as indicated at 1064 in Fig. 2, this type of rocker armpermitting lifting of the valve while the other type of rocker armindicated at 9a causes depression or inward movement of the valve. Bothvalves are operated by pusher rods such as shown at 11 and these are inturn actuated by the extended cam shaft C, the extension of the camshaft being identical to any ordinary cam shaft with the exception thatdouble lobe cams are employed as shown at 12 and 13, see Fig. 2. This isdue to the fact that the cam shaft operates at a' one to two ratio dueto the four-cycle motor employed. hence requiring two lobes for theactuation of the inlet and discharge valves on the compressor cylindersas the valves must be opened and closed once during each revolution ofthe crank shaft, or in other words, in a manner similar to a twocycleoperation.

The discharge ValXQ 10 is, in this instance, held against its seat bymeans of a helical spring 15 and it is also held against its seat by airunder pressure which is equal to receiver pressure. A check valve 16 ofany suitable construction is interposed between the receiver and thedischarge valve but as this is at a point remote from the valve 10 therewill be an intermediate pocket of air between the check valve 16 and thevalve 10 under a pressure substantially the same as that in thereceiver. If an ordinary valve stem was employed there might beconsiderable leakage, hence a small piston 17 is applied to the upperend of the valve stem. The piston is guided in a bushed cylinder 18 andpiston rings are employed as shown at 19. Vents 20 are formed betweenthe lower end of the cylinder 18 and the chamber 21, hence permittingsurging of air under pressure back and forth as valve 10 is operated.Loss of air due to leakage should be reduced to a minimum and a largearea is provided for dissipation of heat so that sticking or breakage ofthe valve stem should be reduced to a minimum. If any breakage shouldoccur it would be of no material importance in the present instance asthe valve cannot possibly fall into the cylinder and cause damage.

By referring to Fig. 1, it will be noted that a step is formed in thepiston as shown at 5a. This step is provided for the purpose of givingample clearance for the inlet valve which moves inwardly when openingand also to permit the inlet valve to remain open when the unloader isin operation as will hereinafter he described. The step formed in thepiston is substantially the only clearance space formed between the topof the piston and the valves. The clearance space, however, isexceedingly small and in fact is only about twenty-five percent of theclearance usually provided for plate valves of the type heretoforereferred to. It should be noted that a shoulder 57) is formed in oneside of the cylinder adjacent the inlet valve 9. This shoulder serves asa stop and a retainer for the valve 9 in case of stem breakage and assuch should eliminate the danger of the inlet valve falling into thecylinder. In fact it would be impossible for the valve to fall in exceptif the breakage should occur at a point in the valve stem below thevalve guide and as breakage usually takes place above that point thereis comparatively little, if any, danger of the inlet valve falling intothe cylinder.

By referring to Figs. 1 and 2, an unloader mechanism is disclosed. Itcomprises a cylinder 30in which is mounted a piston 31. This piston isconnected with a rod 32 and a spring 33 is interposed between the lowerend of the piston and the cylinder to normally hold the piston in theelevated position shown in Fig. 1. Pivotally secured to the lower end ofthe rod is a link 34. This link is secured to one end of a cam 35 whichis pivoted as at 36. The cam 35 'engagesa collar 37 secured on thepusher rod of the inlet valve and when cam 35 is swung in the directionof arrow a it engages the collar and elevates it together with thepusher rod so as to retain the inlet valve open. In actual practicethere are two cams such as shown at 35 and two links 34, there being onecam and link for each inlet valve and if more than two air compressorcylinders are employed the number of cams and links may beproportionately increased. The unloader piston 31 is operated by a pilotvalve of standard construction. There are a number of different types ofpilot valves, hence no illustration has been made. The pilot valve, asis well known, is connected to the air receiver by a pipe and deliversinstantaneous receiver pressure to the unloading device or piston 31when a predetermined pressure is reached in the receiver. When suchpredetermined pressure is reached air pressure causes piston 31 totravel in a downward direction. Such movement is transmitted throughlinks 34 to the cams 35 and both inlet valves are accordingly opened andheld in their open position, conversely, if the receiver drops below apredetermined pressure the air above piston 31 is instantly released andthe piston is returned to normal position by spring 33. The movement ofthe links 34: and cams 35 is thus reversed and the inlet valves areagain permitted to function in a normal manner.

Summarizing the present invention the following advantages should benoted: First, a compressor unit is provided which is adapted for directconnection or integral construction with an internal combustion motor orthe like; secondly, mechanically actuated valves are provided; third, astandard type of poppet valve with large area and lift is provided;fourth, chances of the valves dropping into the cylinders due tobreakage of the valve stems or otherwise is reduced to a minimum; fifth,clearance space between the piston and the cylinder head or the valvemechanism carried thereby is reduced to a minimum and volumetricefficiency of the compressor should accordingly be great and the overallefliciency proportional; sixth, in a direct connected unit such as hereshown the valves may be operated by an extended cam shaft and byproviding double lobes two-cycle operation is possible; seventh,lubrication of the compressor unit is reduced to a minimum as the enginelubrication system may be extended to take care of the compressor;eighth, the problem of unloading when predetermined receiver pressuresare obtained has also been materially simplified as a simple unloadingmechanism is provided whereby the inlet valves may be held in openposition without interfering with the operation of the cam shaft or thedischarge valves.

While certain features of the present invention are more or lessspecifically described, I wish it understood that various changes may beresorted to within the scope of the appended claims. Similarly, that themate rials and finishes of the several parts employed may be such as themanufacturer may decide, or varying conditions or uses may demand.

Having thus described my invention, what I claim and desire to secure byLetters Patent is- 1. In a structure of the character described afour-cycle internal combustion engine having an extended crank shaft andcam shaft, an air compressor cylinder having a piston driven by theextended crank shaft, an inlet and a discharge valve in communicationwith said cylinder, a pair of camson the extended cam shaft, and meansactuated by said cams whereby the inlet and discharge valves are openedand closed in timed relation to the closed in timed relation to themovements of the piston, an unloader mechanism, and means actuatedthereby to retain the inlet valve in an open position.

3. An air compressor comprising a cylinder, a piston reciprocallymounted therein, an inlet and a discharge valve, said discharge valveopening outwardly and the inlet valve inwardly with relation to thecylinder and said piston having a recess formed therein to provideclearance for the inlet valve, mechanically actuated means whereby thevalves are opened and closedonce during each reciprocal movement of thepiston and in timed relation thereto, an unloader mechanism, and meansactuated thereby retaining the inlet valve in an open position.

4. An air compressor comprising a cylinder, a piston reciprocallymounted therein, an inlet and a discharge valve, said discharge valveopening outwardly and the inlet valve inwardly with relation to thecylinder and said piston having a recess formed therein to provideclearance for the inlet valve, mechanically actuated means whereby thevalves are opened and closed once during each reciprocal movement of thepiston and in timed relation thereto, a receiver in communication withthe discharge valve, a check valve intermediate the discharge valve andthe receiver, an unloader mechanism, and means actuated thereby forretaining the inlet valve in an open position.

5. In a compressor of the character described a cylinder and a head, adischarge valve mounted in the head and opening outwardly with relationto the cylinder, a stem secured to the valve, a piston secured on thestem, a cylinder in the head through which the valve stem projects andin which the valve stem piston reciprocates, a spring normally retainingthe valve in closed position, and mechanically actuated means foropening the valve against sprin tension.

6. In a compressor of the character de scribed, a cylinder and pistonreciprocally mounted therein, an inlet and a discharge valve incommunication with the cylinder, a pair of rocker arms one for eachvalve, pusher rods whereby the rocker arms are ac tuated to open thevalves, a pivotally mounted cam, an unloader mechanism, means Wherebymovement is transmitted from the unloader to swing the cam about itspivot, and a collar on the inlet valve pusher rod With which said camengages to retain the inlet valve in an open position.

7. In a compressor of the character described, a valve, a seat withWhich'it co-operates, a stemon the valve, a piston secured to the stem,a cylinder through which the valve stem extends and in Which the pistonoperates, a spring normally retaining the valve in closed position onits seat, and a rocker arm engageable With the stem and adapted to openthe Valve.

AUSTIN J. RIX.

